复杂多端柔直配电网短路故障全过程全网特征量计算方法  

Short-circuit Calculation Method of Whole Network Characteristic Quantity During the Whole Fault Process in Complex Multi-terminal Flexible DC Distribution Network

作　　者：戴志辉 李涵伟 李毅然 DAI Zhihui;LI Hanwei;LI Yiran(State Key Laboratory of Alternate Electrical Power System with Renewable Energy Resources,North China Electric Power University,Baoding 071003,China)

机构地区：[1]新能源电力系统国家重点实验室(华北电力大学),保定071003

出　　处：《高电压技术》2024年第11期4837-4849,I0004,I0005,共15页High Voltage Engineering

基　　金：国家自然科学基金(51877084)。

摘　　要：多端柔直配电网短路阻尼小、惯性低,系统中存在大量电力电子器件使得故障发展呈强非线性、阶段性特征,传统短路计算方法关注“点”和“线”的故障特征,难以顾及“网”级特性。为此,着眼短路故障从电容放电到交流侧馈流发展的全过程,系统引入直流故障口理论,首先利用阻抗的高频特性将故障网络合理化简,再经拉普拉斯反变换后得到电容放电阶段的故障电流时域近似解,并通过故障口阻抗求得全网特征量;在交流稳态馈流阶段,建立了换流器端口转移矩阵,经换相重叠修正后消去网络中的混联节点,进而得到适用于多端柔直配电网的稳态短路计算方法。最后,基于PSCAD/EMTDC平台搭建仿真模型,验证了不同故障位置及过渡电阻下所提短路计算方法的准确性。Multi-terminal flexible DC distribution network has small short-circuit damping and low inertia,and the fault development presents the characteristics of strong nonlinearity and stage due to the existance of a large number of power electronic devices in the system.Conventional short-circuit calculation methods concern fault characteristics of“points”and“lines”,making it difficult to consider the network-level characteristics.Therefore,this paper focuses on the whole process of short-circuit fault from capacitor discharge to AC-side feed current,and introduces the theory of DC fault ports.On this basis,the fault network is simplified by using high-frequency equivalent characteristics,and then the approximate solution of the fault current in the capacitor discharge stage is obtained by the Laplace inverse transformation.Subse-quently,the characteristic quantity of the whole network is obtained by fault-port impedance.In the steady-state AC feed stage,the converter port transfer matrix is established,the series-connected nodes in the network are eliminated after commutation overlap correction,and then the steady-state short-circuit calculation method suitable for multi-terminal flexible DC power grids is obtained.Finally,a simulation model is built based on PSCAD/EMTDC platform,which verifies the accuracy of the proposed short circuit calculation method under different fault locations and fault resistances.

关 键 词：多端柔直配电网 短路计算 故障口 高频等效 换相重叠 

分 类 号：TM73[电气工程—电力系统及自动化]